Japanese nuclear plant hit by massive explosion

Earthquake-stricken country on nuclear alert, although officials say container housing reactor was n

A Japanese nuclear power plant has been hit by a massive explosion after Friday's devastating earthquake.

Television pictures showed huge billows of smoke coming from the plant at Fukushima and four workers were injured.

The Prime Minister, Naoto Kan, declared a state of emergency at the Fukushima Daiichi and Daini (also known as Fukushima 1 and 2) power plants while engineers attempted to confirm whether a reactor had gone into meltdown.

Officials say the container housing the reactor was not damaged and that radiation levels have now fallen.

However, Japanese authorities are preparing to distribute iodine - which helps protect the body from radioactive exposure - to residents in the area of both the nuclear plants.

A huge relief operation is underway in Japan after the 8.9 magnitude earthquake and tsunami. The official death toll now stands at 574, with 586 people declared missing and 1,105 injured. All those figures are likely to rise dramatically.